Energy & Environmental Materials最新文献

Due to the push for carbon neutrality in various human activities, the development of methods for producing electricity without relying on chemical reaction processes or heat sources has become highly significant. Also, the challenge lies in achieving microwatt-scale outputs due to the inherent conductivity of the materials and diverting electric currents. To address this challenge, our research has concentrated on utilizing nonconductive mediums for water-based low-cost microfibrous ceramic wools in conjunction with a NaCl aqueous solution for power generation. The main source of electricity originates from the directed movement of water molecules and surface ions through densely packed microfibrous ceramic wools due to the effect of dynamic electric double layer. This occurrence bears resemblance to the natural water transpiration in plants, thereby presenting a fresh and straightforward approach for producing electricity in an ecofriendly manner. The generator module demonstrated in this study, measuring 12 × 6 cm², exhibited a noteworthy open-circuit voltage of 0.35 V, coupled with a short-circuit current of 0.51 mA. Such low-cost ceramic wools are suitable for ubiquitous, permanent energy sources and hold potential for use as self-powered sensors and systems, eliminating the requirement for external energy sources such as sunlight or heat.

Skin-like electronics research aiming to mimic even surpass human-like specific tactile cognition by operating perception-to-cognition-to-feedback of stimulus to build intelligent cognition systems for certain imperceptible or inappreciable signals was so attractive. Herein, we constructed an all-in-one tri-modal pressure sensing wearable device to address the issue of power supply by integrating multistage microstructured ionic skin (MM i-skin) and thermoelectric self-power staffs, which exhibits high sensitivity simultaneously. The MM i-skin with multi-stage “interlocked” configurations achieved precise recognition of subtle signals, where the sensitivity reached up to 3.95 kPa⁻¹, as well as response time of 46 ms, cyclic stability (over 1500 cycles), a wide detection range of 0–200 kPa. Furthermore, we developed the thermoelectricity nanogenerator, piezoelectricity nanogenerator, and piezocapacitive sensing as an integrated tri-modal pressure sensing, denoted as P-iskin, T-iskin, and C-iskin, respectively. This multifunctional ionic skin enables real-time monitoring of weak body signals, rehab guidance, and robotic motion recognition, demonstrating potential for Internet of things (IoT) applications involving the artificial intelligence-motivated sapiential healthcare Internet (SHI) and widely distributed human-machine interaction (HMI).

The intense research of lithium-ion batteries has been motivated by their successful applications in mobile devices and electronic vehicles. The emerging of intelligent control in kinds of devices brings new requirements for battery systems. The high-energy lithium batteries are expected to respond or react under different environmental conditions. In this work, a tri-salt composite electrolyte is designed with a temperature switch function for intelligently temperature-controlled lithium batteries. Specifically, the halide Li₃YBr₆ together with LiTFSI and LiNO₃ works as active fillers in a low-melting-point polymer matrix (polyethyleneglycol dimethyl ether (PEGDME) and polyethylene oxide (PEO)), which is further filled into the pre-lithiated alumina fiber skeleton. Above 60 °C, the composite electrolyte exists in the liquid state and fully contacts with the working electrodes on the liquid–solid interface, effectively minimizing the interfacial resistance and leading to high discharge capacity in the cell. The electrolyte is changed into a solid state below 30 °C so that the ionic conductivity is significantly reduced and the interface resistance is increased dramatically on the solid–solid interface. Therefore, by simply adjusting the temperature, the cell can be turned “ON” or “OFF” intentionally. This novel function of the composite electrolyte has enlightening significance in developing intelligently temperature-controlled lithium batteries.

We employ advanced first principles methodology, merging self-consistent phonon theory and the Boltzmann transport equation, to comprehensively explore the thermal transport and thermoelectric properties of KCdAs. Notably, the study accounts for the impact of quartic anharmonicity on phonon group velocities in the pursuit of lattice thermal conductivity and investigates 3ph and 4ph scattering processes on phonon lifetimes. Through various methodologies, including examining atomic vibrational modes and analyzing 3ph and 4ph scattering processes, the article unveils microphysical mechanisms contributing to the low κ_L within KCdAs. Key features include significant anisotropy in Cd atoms, pronounced anharmonicity in K atoms, and relative vibrations in non-equivalent As atomic layers. Cd atoms, situated between As layers, exhibit rattling modes and strong lattice anharmonicity, contributing to the observed low κ_L. Remarkably flat bands near the valence band maximum translate into high PF, aligning with ultralow κ_L for exceptional thermoelectric performance. Under optimal temperature and carrier concentration doping, outstanding ZT values are achieved: 4.25 (a(b)-axis, p-type, 3 × 10¹⁹ cm⁻³, 500 K), 0.90 (c-axis, p-type, 5 × 10²⁰ cm⁻³, 700 K), 1.61 (a(b)-axis, n-type, 2 × 10¹⁸ cm⁻³, 700 K), and 3.06 (c-axis, n-type, 9 × 10¹⁷ cm⁻³, 700 K).

Transition metal phosphides (TMPs) have emerged as an alternative to precious metals as efficient and low-cost catalysts for water electrolysis. Elemental doping and morphology control are effective approaches to further improve the performance of TMPs. Herein, Fe-doped CoP nanoframes (Fe-CoP NFs) with specific open cage configuration were designed and synthesized. The unique nano-framework structured Fe-CoP material shows overpotentials of only 255 and 122 mV at 10 mA cm⁻² for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively, overwhelming most transition metal phosphides. For overall water splitting, the cell voltage is 1.65 V for Fe-CoP NFs at a current density of 10 mA cm⁻², much superior to what is observed for the classical nanocubic structures. Fe-CoP NFs show no activity degradation up to 100 h which contrasts sharply with the rapidly decaying performance of noble metal catalyst reference. The superior electrocatalytic performance of Fe-CoP NFs due to abundant accessible active sites, reduced kinetic energy barrier, and preferable *O-containing intermediate adsorption is demonstrated through experimental observations and theoretical calculations. Our findings could provide a potential method for the preparation of multifunctional material with hollow structures and offer more hopeful prospects for obtaining efficient earth-abundant catalysts for water splitting.

Emerging as a new class of two-dimensional materials with atomically thin layers, MBenes have great potential for many important applications such as energy storage and electrocatalysis. Toward mitigating carbon footprint, there has been increasing interest in CO₂/CO conversion on MBenes, but mostly focused on C₁ products. C₂₊ chemicals generally possess higher energy densities and wider applications than C₁ counterparts. However, C–C coupling is technically challenging because of high energy requirement and currently few catalysts are suited for this process. Here, we explore electrochemical CO reduction reaction to C₂ chemicals on Mo₂B₂O₂ MBene via density-functional theory calculations. Remarkably, the most favorable CO–COH coupling is revealed to be a spontaneous and barrierless process, making Mo₂B₂O₂ an efficient catalyst for C–C coupling. Among C₁ and C₂ chemicals, ethanol is predicted to be the primary product. Furthermore, by charge and bond analysis, it is unraveled that there exist significantly more unbonded electrons in the C atom of intermediate *COH than other C₁ intermediates, which is responsible for the facile C–C coupling. From an atomic scale, this work provides microscopic insight into C–C coupling process and suggests Mo₂B₂O₂ a promising catalyst for electrochemical CO reduction to C₂ chemicals.

Lithium-ion batteries (LIBs) play a pivotal role in today's society, with widespread applications in portable electronics, electric vehicles, and smart grids. Commercial LIBs predominantly utilize graphite anodes due to their high energy density and cost-effectiveness. Graphite anodes face challenges, however, in extreme safety-demanding situations, such as airplanes and passenger ships. The lithiation of graphite can potentially form lithium dendrites at low temperatures, causing short circuits. Additionally, the dissolution of the solid-electrolyte-interphase on graphite surfaces at high temperatures can lead to intense reactions with the electrolyte, initiating thermal runaway. This review introduces two promising high-safety anode materials, Li₄Ti₅O₁₂ and TiNb₂O₇. Both materials exhibit low tendencies towards lithium dendrite formation and have high onset temperatures for reactions with the electrolyte, resulting in reduced heat generation and significantly lower probabilities of thermal runaway. Li₄Ti₅O₁₂ and TiNb₂O₇ offer enhanced safety characteristics compared to graphite, making them suitable for applications with stringent safety requirements. This review provides a comprehensive overview of Li₄Ti₅O₁₂ and TiNb₂O₇, focusing on their material properties and practical applicability. It aims to contribute to the understanding and development of high-safety anode materials for advanced LIBs, addressing the challenges and opportunities associated with their implementation in real-world applications.

Machine learning (ML) integrated with density functional theory (DFT) calculations have recently been used to accelerate the design and discovery of single-atom catalysts (SACs) by establishing deep structure–activity relationships. The traditional ML models are always difficult to identify the structural differences among the single-atom systems with different modification methods, leading to the limitation of the potential application range. Aiming to the structural properties of several typical two-dimensional MA₂Z₄-based single-atom systems (bare MA₂Z₄ and metal single-atom doped/supported MA₂Z₄), an improved crystal graph convolutional neural network (CGCNN) classification model was employed, instead of the traditional machine learning regression model, to address the challenge of incompatibility in the studied systems. The CGCNN model was optimized using crystal graph representation in which the geometric configuration was divided into active layer, surface layer, and bulk layer (ASB-GCNN). Through ML and DFT calculations, five potential single-atom hydrogen evolution reaction (HER) catalysts were screened from chemical space of 600 MA₂Z₄-based materials, especially V₁/HfSn₂N₄(S) with high stability and activity (ΔG_H* is 0.06 eV). Further projected density of states (pDOS) analysis in combination with the wave function analysis of the SAC-H bond revealed that the SAC-dz² orbital coincided with the H-s orbital around the energy level of −2.50 eV, and orbital analysis confirmed the formation of σ bonds. This study provides an efficient multistep screening design framework of metal single-atom catalyst for HER systems with similar two-dimensional supports but different geometric configurations.

α-Keggin polyoxometalates (POMs) [XW₁₂O₄₀]ⁿ⁻ (X = Al, Si, P, S) are widely used in batteries owing to their remarkable redox activity. However, the mechanism underlying the applications appears inconsistent with the widely accepted covalent bonding nature. Here, first-principles calculations show that XW₁₂ are core–shell structures composed of a shell and an XO₄ⁿ⁻ core, both are stabilized by covalent interactions. Interestingly, owing to the presence of a substantial number of electrons in W₁₂O₃₆ shell, the frontier molecular orbitals of XW₁₂ are not only strongly delocalized but also exhibit superatomic properties with high-angular momentum electrons that do not conform to the Jellium model. Detailed analysis indicates that energetically high lying filled molecular orbitals (MOs) have reached unusually high-angular momentum characterized by quantum number K or higher, allowing for the accommodation of numerous electrons. This attribute confers strong electron acceptor ability and redox activity to XW₁₂. Moreover, electrons added to XW₁₂ still occupy the K orbitals and will not cause rearrangement of the MOs, thereby maintaining the stability of these structures. Our findings highlight the structure–activity relationship and provide a direction for tailor-made POMs with specific properties at atomic level.

Metal-covalent organic frameworks (MCOF) as a bridge between covalent organic framework (COF) and metal organic framework (MOF) possess the characteristics of open metal sites, structure stability, crystallinity, tunability as well as porosity, but still in its infancy. In this work, a covalent organic framework DT-COF with a keto-enamine structure synthesized from the condensation of 3,3′-dihydroxybiphenyl diamine (DHBD) and triformylphloroglucinol (TFP) was coordinated with Cu²⁺ by a simple post-modification method to a obtain a copper-coordinated metal-covalent organic framework of Cu-DT COF. The isomerization from a keto-enamine structure of DT-COF to a enol-imine structure of Cu-DT COF is induced due to the coordination interaction of Cu²⁺. The structure change of Cu-DT COF induces the change of the electron distribution in the Cu-DT COF, which greatly promotes the activation and deep Li-storage behavior of the COF skeleton. As anode material for lithium-ion batteries (LIBs), Cu-DT COF exhibits greatly improved electrochemical performance, retaining the specific capacities of 760 mAh g⁻¹ after 200 cycles and 505 mAh g⁻¹ after 500 cycles at a current density of 0.5 A g⁻¹. The preliminary lithium storage mechanism studies indicate that Cu²⁺ is also involved in the lithium storage process. A possible mechanism for Cu-DT COF was proposed on the basis of FT-IR, XPS, EPR characterization and electrochemical analysis. This work enlightens a novel strategy to improve the energy storage performance of COF and promotes the application of COF and MCOF in LIBs.